The invention concerns a method of editing in the storage of a data processing system character and/or image information to be represented in dot pattern lines on a page (or image screen) of a recording medium. Various print processes are known, wherein characters and graphical data are recorded in the form of dot patterns. Such dot patterns may be generated, for example, by mosaic (needle) printers, metal paper printers, laser printers or raster displays. All of these recording processes provide for a dot-shaped recording to be generated by suitable print elements or for print beams to be controlled so as to generate such a recording.
The printout of pages with text and/or graphical information (hereinafter collectively referred to as "information") substantially depends on the layout, i.e., the way in which text and image blocks (hereinafter collectively referred to as "blocks") are arranged relative to each other on a page (or image screen).
By means of data processing systems and the above-mentioned output units driven by them the information to be recorded is initially edited in the storage of the data processing system. A CPU (Central Processing Unit) controls the data processing systems and the output units. Such a storage consists of a plurality of storage cells (bits), each storing the information of a picture element to be printed (subsequently referred to as pel which is short for the term "picture element". Thus, the page to be printed is initially edited in storage dot-by-dot before each stored pel can be printed at its predetermined position on the page. Such a print storage would have to be enormous, particularly for high resolution print methods. Print pages with some 33 million pels are not seldom, i.e., the print storage, if it were to reproduce an entire page bit-by-bit would have to have a capacity of 33 million bits.
However, with such an approach the size of the print storage would become excessive.
For modern data processing systems, such storage sizes would be inexpedient; even in the case of a virtual storage concept, certain disadvantages could not be ignored. Virtual, in this context, means that the data processing system has an extremely large external storage and that the information of this external storage is read in blocks into the work storage of the data processing system where it is processed. In other words, a page to be edited can be stored in bits in an external storage, but for editing such a page in work storage, the respective page blocks would have to be read in and then read out, which is rather time-consuming.
From German Offenlegungsschrift OS No. 25 16 332, a method is known for coding electrical signals which are obtained upon scanning a graphical pattern comprising text and images. For this purpose, the graphical pattern is divided into sub-areas and coding of the electrical signals obtained upon scanning the sub-areas, substantially containing image and text data, is effected by means of an image and text code, respectively.
In German Offenlegungsschrift OS No. 28 25 321 on an all-points-addressable printer is described for printing characters of different sizes and/or typefonts at arbitrary positions on a page either from right to left or from top to bottom. This printer is also suitable for graphical representations.
In U.S. Pat. No. 3,828,319, a system is described for generating a dot pattern image from binary signals supplied by a computer. This system uses so-called push-down storages, consisting of two separate registers, for merging information.
Furthermore, German Offenlegungsschrift OS No. 21 61 038 describes a method of generating data for producing screened rotary type forms, wherein screen dots are recorded on the print form as adjacent lines. Data for recording the screen dots are derived, according to the respective screen selected, from character and image masters and stored as data groups in one or several first storages. The data groups of characters and images to be recorded are fetched from the first storage(s), sorted according to the sequence in which they are to be recorded and stored in buffers from where they are fetched as image lines, belonging to the same recording lines, to control the continuous recording process at the clock of the selected screen.
In German Offenlegungsschrift OS No. 27 24 199, a system is described for optically reproducing symbols, characters, and representations, in particular for the layout of advertisements in newspapers and the like. For accommodating information, this system is provided with terminal control means transmitting data, control signals, addresses, and time clock signals to a common logical control associated with the system. This logical control is associated with a computer for processing the data, addresses, and time clock pulses received.
In German Offenlegungsschrift OS No. 27 24 075, a system is described for optically reproducing symbols, characters and representations, in particular for the layout of advertisements in newspapers and the like, using a common logical control and display units. For this purpose, predetermined stored signals as well as subsequently stored variable signals, associated with symbols, characters, and representations, are combined in the common, logical control. Optical reproduction is effected by image storage means associated with this control.
The processes that have become known so far for editing a page to be printed require either too much storage space or time.
Methods and systems for print data editing other than those mentioned are often too specific or necessitate special extensive circuitry.
To overcome these disadvantages, it is the object of the invention to provide an approach requiring only relatively little storage space for rapidly editing print data in the storage of the data processing system.
This object is accomplished by the measures specified in the characterizing part of claim 1.
Preferred embodiments of the method in accordance with the invention will be seen from the subclaims.